Until now, a mere tweet-of-confidence from Elon Musk has been enough to get Bitcoin's price spiking. Not any more. The tide of negative news on its carbon footprint and hostility from the Chinese government appear to be overwhelming any praise the Tesla chief can heap on the leading cryptocurrency. And if the EV-maker's celebrated Bitcoin bet goes bad––it's on the verge right now––the aftershock will further quash the frenzy that's already fading.

Keep in mind that Musk himself could hasten Bitcoin's decline. He's demanding that the energy-intensive mining process get a lot greener, and if that doesn't happen, his enthusiasm could turn to disdain.

On Sunday, June 13, Elon Musk famously rode to Bitcoin's rescue. At the time, its price was stuck in the mid-$30,000s after collapsing as much as 50% in May from its all-time high of almost $65,000. Exactly a month earlier, the Tesla CEO had helped spark the selloff by tweeting that the EV-maker would no longer accept Bitcoin as payment for its cars. But on June 13, he reversed course, posting that Tesla would resume taking Bitcoin from its customers "when there's confirmation of reasonable (approximately 50%) clean energy usage by miners."

Musk's change of heart boosted Bitcoin's flagging fortunes. Within two days, it was changing hands at $42,295, a gain of 14% that added a stunning $175 billion to its market cap. But this time, the Elon bounce lasted only a few days. News of a severe crackdown in the China, far and away the biggest nation for Bitcoin mining, sent prices reeling. All three of the provinces that host most of the production, Xinjiang, Sichuan, and Yunnan, unveiled campaigns to banish the industry, and the Central Bank of China ordered banks to ban Bitcoin transactions, declaring that "speculative trading in virtual currencies risks criminal activities such as illegal asset transfers and money laundering."

By midday on Monday, June 21, Bitcoin was selling at $32,800. That's 11.6% below its price when Musk issued his rescue tweet, and almost a quarter under the highs reached two days later. Bitcoin is now flirting with its 2021 intraday low of $30,682, posted on April 14.

Bitcoin's decline has already undermined the big Musk endorsement that set the great rally in motion—Tesla's purchase of $1.5 billion in coins between the start of 2021 and early February, a gambit cloaked in praise by Musk and CFO Zach Kirkhorn. By Fortune’s estimate, Tesla originally bought 46,000 coins at an average price of $32,610. Later in Q1, it sold 10% of its holdings, or around 4,600 Bitcoins, for $271 million, $128 million more than it paid. At the end of March, its treasury harbored the remaining 41,400 coins at a "carrying value" of $1.33 billion. Hence, the average cost basis for every Bitcoin now on Tesla's books is $32,126. (That's slightly less than the average price it paid; because of the specifics of Tesla's Bitcoin accounting, it also took a $27 million charge on the investment in Q1, which slightly lowered the cost basis on the coins that remain.)

So at the current price of $32,800, Tesla's holdings are hovering just above the breakeven number of $32,126. Another drop of 2% or more would send its portfolio underwater. What a comedown! At Bitcoin's summit of $65,000 just over two months ago, Tesla's stash was worth $1.355 billion. No less than $1.33 billion in paper gains have vanished in the sudden swoon, equivalent to 80% of the pretax profits Tesla garnered from selling cars and batteries in its past five quarters.

Of course, Tesla hasn't actually lost money, at least not yet. It's still sitting on realized and unrealized gains totaling around $130 million, consisting almost entirely of the profit on the 10% it sold. But who knows where Bitcoin will be trading when the second quarter ends on June 30? If the tailspin continues, Tesla will need to book losses; at $28,000, that "impairment" could be $200 million.

Watching Bitcoin deficits eroding the slender profits from selling EVs will distress investors. They'll wonder how such a brilliant visionary as Elon Musk could make a super-risky stock even riskier by wagering on the most volatile, controversial "asset" in modern history. Musk's past tweets achieved the dual mission of bailing out the glamorous regime of Bitcoin enthusiasts and keeping the value of Tesla's portfolio in the black. Musk has proved that charismatic influencers can convince folks that something with no practical uses is worth a king's ransom. But as we're now seeing, that pitch is a sand castle that wave after wave of bad news is washing away.